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A New Analytical Method for the Kinetic Spectrophotometric Determination of Trace Amounts of Nitrite in Some Environmental Water Samples
(Modestum Ltd, 2010) Gurkan, Ramazan; Ulusoy, Halil Ibrahim; Akcay, Mehmet
Nitrite is a characteristic pollutant ion, which is ubiquitous within environmental and physiological systems, and occurs in water as an intermediate during the nitrogen cycle. Therefore, the detection and determination of its concentration at trace levels is extremely important in biological and environmental studies. A simple, sensitive and rapid kinetic spectrophotometric method for the determination of nitrite in different natural and wastewater samples is presented. The reaction is initiated by adding the known volumes of a nitrite ion solution of identified concentration to acid solutions of Cresyl violet perchlorate, which the color of indicator reagent changes to yellow with time. Then, the absorbance changes are monitored spectrophotometrically at lambda(max) = 585 nm for the concentration range of 0.01-2 mu g mL(-1) and at lambda(max)= 409 nm for the concentration range of 0.5-5 mu g mL(-1) of nitrite ion at 40 degrees C. The detection limit and quantification limit of the proposed kinetic method were 0.00627 and 0.0188 mu g mL-1 respectively. The RSDs for the determination of 0.2 and 1.5 mu g ml(-1) of nitrite were 4.98% and 2.08% for five replicate measurements, respectively. The effect of possible interfering ions on the determination of nitrite is described. Many of cations and anions have no interfering effect but Fe3+, Fe2+, Cd2+, I-, N-3(-), WO42-, S-2(-), SO32-and S2O32- ions do interfere. The accuracy and validity of the proposed kinetic method was established by studying recovery of spiked nitrite ion and by parallel determination using a standard method based on diazo-coupling reaction. The method was successfully applied to the determination of nitrite in various natural and wastewater samples.
A new ion-pair ultrasound assisted-cloud point extraction approach for determination of trace V(V) and V(IV) in edible vegetal oils and vinegar by spectrophotometry
(Elsevier, 2019) Temel, Nuket Kartal; Kus, Berna; Gurkan, Ramazan
A new ion-pair ultrasound-assisted-cloud point extraction (UA-CPE) procedure for the preconcentration and determination of V(V) and V(IV) in edible vegetal oils and vinegar by spectrophotometry at 530 nm was developed. The method is based on selective and sensitive anionic chelation of V(V) and V(IV) with EDTA, and then a stable ion-pair formation of the formed chelate complexes with cationic phenazine dye, Safranin T, at pH 4.0 and/or pH 5.0 respectively, which can be easily extracted into the micellar phase of Triton X-114 with the help of ultrasound energy. The variables affecting ion-pair formation and extraction efficiency were evaluated and optimized. Under the optimized conditions, there was a linear relationship in range of 1-40 mu g/L for V(IV) at pH 5.0 with higher calibration sensitivity while it obtained a rectilinear behavior in the range of 2-180 mu g/L for V(V) at pH 4.0. The limits of detection and quantification for V(IV) were 0.26 and 0.85 mu g/L with a sensitivity enhancement of 83.6 from preconcentration of 35-mL sample, respectively where these values are 0.53 and 1.77 mu g/L, respectively, for V(V). The recovery rate and precision for five replicate measurements of 5, 25 and 100 mu g/L V(V) and V(IV) were in range of 98-101%, 3.1-4.2% and 3.2-4.5%, respectively. The accuracy was statistically verified by analysis of a certified oil sample with both the developed method and independent comparison method, and the method was successfully applied to the analysis of total V contents of edible vegetal oils and vinegar samples after preconcentration.
A novel, green and safe ultrasound-assisted emulsification liquid phase microextraction based on alcohol-based deep eutectic solvent for determination of patulin in fruit juices by spectrophotometry
(Academic Press Inc Elsevier Science, 2019) Altunay, Nail; Elik, Adil; Gurkan, Ramazan
In the study, a novel, green and safe microextraction procedure was developed for the determination and extraction of patulin, alpha,beta-unsaturated lactone (4-hydroxy-4H-furo[3,2-c] pyran-2-(6H)-one), in fruit juice samples by using ultrasound-assisted emulsification liquid phase microextraction based on alcohol-based deep eutectic solvent coupled to micro-volume ultraviolet-visible spectrophotometry. The method is based on formation of chelate complex or nucleophilic adduct formation between patulin and Mg(II) in presence of nucleophilic metal chelating tris-buffer at pH 8.0, and then extraction of the formed complex into the micro-drops of deep eutectic solvent by donor-acceptor mechanism. The optimum conditions for the effective extraction of patulin from fruit juices were 500 mu L of deep eutectic solvent, 75 mu mol L-1 of Mg(II) solution, pH 8.0, ultrasound time of 12 min, respectively. The patulin in enriched phase was detected by micro-volume ultraviolet-visible spectrophotometry at 304 nm. Under optimal conditions, the linear response range of the method was from 7.5 to 420 mu g L-1 with a detection limit of 2.2 mu g L-1. After the validation study, the applicability of the method were tested by analysis of the fruit juice samples. The average recovery for spiked fruit juices was ranged from 90.2% to 106.9%, with relative standard deviations lower than 4.2%.
A RELIABLE METHOD OF QUANTIFICATION OF TRACE COPPER IN BEVERAGES WITH AND WITHOUT ALCOHOL BY SPECTROPHOTOMETRY AFTER CLOUD POINT EXTRACTION
(Soc Brasileira Quimica, 2013) Gurkan, Ramazan; Altunay, Nail
A new cloud point extraction (CPE) method was developed for the separation and preconcentration of copper (II) prior to spectrophotometric analysis. For this purpose, 1-(2,4-dimethylphenyl) azonapthalen-2-ol (Sudan II) was used as a chelating agent and the solution pH was adjusted to 10.0 with borate buffer. Polyethylene glycol tert-octylphenyl ether (Triton X-114) was used as an extracting agent in the presence of sodium dodecylsulphate (SDS). After phase separation, based on the cloud point of the mixture, the surfactant-rich phase was diluted with acetone, and the enriched analyte was spectrophotometrically determined at 537 nm. The variables affecting CPE efficiency were optimized. The calibration curve was linear within the range 0.285-20 mu g L-1 with a detection limit of 0.085 mu g L-1. The method was successfully applied to the quantification of copper in different beverage samples.
Application of simple, fast and eco-friendly ultrasound-assisted-cloud point extraction for pre-concentration of zinc, nickel and cobalt from foods and vegetables prior to their flame atomic absorption spectrometric determinations
(TAYLOR & FRANCIS LTD, 2018) Altunay, Nail; Elik, Adil; Bulutlu, Cuneyt; Gurkan, Ramazan
In this study, a simple, fast and eco-friendly ultrasound-assisted-cloud point extraction method for extraction and pre-concentration of zinc, nickel and cobalt from vegetables and foods prior to their determination by flame atomic absorption spectrometry (FAAS) was proposed. Ultrasound energy was used to shorten extraction time and reduce steps needed or to improve selectivity. The method is based on complex formation of metal ions with carmine in presence of cationic surfactant at pH 5.0, and then extraction of their hydrophobic complexes into the micellar phase of Igepal CO-630 as extractant. After optimisation, calibration curves for Zn, Co and Ni were linear in the range of 2-120, 2-220 and 2-180 g kg(-1), respectively. Limits of detection, which is described as ratio of 3xstandard deviation of 12 replicate measurements of blank analysis to slope of calibration curves, were 0.5, 0.6 and 0.6 g kg(-1) for Zn, Ni and Co, respectively. Relative standard deviations (RSDs%, n: 5) for 25 g kg(-1) of each analyte were less than 3.1%. The recovery rate was higher than 94% with a lower RSD than 3.1% for five replicate measurements of 25 g kg(-1) of each analyte. The accuracy was verified using two different standard reference materials (SRM 1570a-Trace elements in spinach leaves and SRM 1548a-Typical diet), and the results were in good agreement with the certified values. The method was applied to the determinations of Zn, Ni and Co in vegetables and foods by FAAS.
Application of ultrasonic-assisted cloud point extraction/flame atomic absorption spectrometry (UA-CPE/FAAS) for preconcentration and determination of low levels of antimony in some beverage samples
(SPRINGER, 2016) Gurkan, Ramazan; Eser, Merve
Due to be able to migrate or leach from food packaging materials into the foods and/or beverages, development of a new, sensitive and selective analytical methods for low levels of antimony as a food contaminant is of great importance in terms of food safety. In this context, an ultrasonic-assisted cloud point extraction method was developed for the preconcentration and determination of antimony as Sb(III) using 4-(2-thiazolylazo)resorcinol (TAR) and 2-(2-thiazolylazo)-p-cresol (TAC) as chelating agents and sodium dodecyl sulfate as signal enhancing agent at pH 6.0 and mediated by nonionic surfactant, t-octylphenoxypolyethoxyethanol by flame atomic absorption spectrometry. Using the optimized conditions, the calibration curves obtained from Sb(III) with TAR and TAC were linear in the concentration ranges of 0.5-180 and 1-180 mu g L-1 with detection limits of 0.13 and 0.28 mu g L-1, respectively. The precision (as relative standard deviations, RSDs) was lower than 3.9 % (25 and 100 mu g L-1, n: 6). The method accuracy was validated by the analysis of two standard reference materials. The results obtained were statistically in a good agreement with the certified values at 95 % confidence limit. The method has successfully been applied to the determination of Sb(III) and total Sb in selected beverages, milk and fruit-flavored milk products before and after pre-reduction of Sb(V) to Sb(III) with a mixture of KI/ascorbic acid in acidic media. The Sb(V) contents of samples were quantitatively calculated from analytical difference between total Sb and Sb(III) levels.
Application of Ultrasound-Assisted Cloud-Point Extraction and Spectrophotometry for Preconcentration and Determination of Trace Amounts of Copper(II) in Beverages
(Pleiades Publishing Inc, 2019) Temel, Nuket Kartal; Gurkan, Ramazan
A new method for preconcentration of trace Cu(II) in beverages before determination by spectrophotometry is presented. The method is based on the ternary complex formation of Cu(II) with Safranin T in presence of pyrogallol at pH 5.5 followed by its extraction into the micellar phase of Triton X-114. The ternary complex was monitored by spectrophotometry at 532 nm. Variables affecting extraction efficiency were evaluated and optimized. Under the optimal conditions, the detection limit was 0.6 mu g/L in the range of 2-300 mu g/L with sensitivity enhancement of 55 after preconcentration from 15 mL of the sample, and precision was in the range of 2.5-3.9%. The accuracy was verified by the analysis of two certified samples and recovery studies of the spiked samples. The intra- and inter-day precision varied in the ranges of 3.7-4.6 and 3.9-5.2%, respectively. The method was successfully applied to determination of trace Cu(II) in beverages.
Bio-sorption of bisphenol a by the dried- and inactivated-lichen (Pseudoevernia furfuracea) biomass from aqueous solutions
(Springer, 2020) Senol, Zeynep Mine; Gul, Ulkuye Dudu; Gurkan, Ramazan
Bisphenol A (BPA), which is known as one of the endocrine-disrupting chemicals (EDCs) with hydrophilic hydroxyl groups and hydrophobic aromatic groups, has been widely used in plastic industries. The chemical waste from the industry is sometimes discharges into lakes and rivers, and then these surface waters can be polluted. So, this article aims to investigate the bio-sorption process of BPA by the inactivated lichen (Pseudoevernia furfuracea) biomass from aqueous solution. At initial, the effect of the variables such as initial BPA concentration, solution pH, temperature, contact time and recovery rate on the bio-sorption process was investigated. From the optimal results, it has been observed that the highest removal efficiency is approximately 64% at a contact time of 3-h, the bio-sorbent concentration of 9 mg/L, initial BPA concentration of 40 mg/L, and agitation speed of 150 rpm at pH 5.0. In explaining the bio-sorption potential of lichen biomass, Langmuir and/or Redlich-Peterson isotherms with two and three parameters, respectively were observed to be better fit with the experimental isotherm data (R-2 = 0.982). From equilibrium data based on difference between the measured and predicted results (q(e, exp)and q(e, pre)), it was shown that biosorption of BPA could be best described by the pseudo second order kinetic model with minimum sum of square error of 2.61%. In addition, it shows more film diffusion, and partly pore diffusion in linearity region in terms of kinetic sorption behaviors of BPA in the rate-limiting step as well as intra-particle diffusion according to Boyd's kinetic model with better regression coefficient than 0.981 when compared to the other used kinetic models, including Bangham's pore diffusion and Elovich kinetic models (with R(2)of 0.958 and 0.929). The thermodynamic studies showed that the biosorption process was spontaneous, and chemically feasible. Therefore, due to be low-cost, eco-friendly character, wide availability and easily accessible, the lichen biomass could be used as a promising bio-sorbent for the removal of BPA from the environment and wastewater effluents.
CATALYTIC SPECTROPHOTOMETRIC DETERMINATION OF Mn(II) AT TRACE LEVELS USING CELESTINE BLUE-KIO4-1,10-PHENANTROLINE REDOX REACTION
(Chem Soc Ethiopia, 2011) Gurkan, Ramazan
A new kinetic method has been developed for the measurement of Mn(II) in water samples. The method is based on the catalytic effect of Mn(II) with the oxidation of Celestine blue (CB+) by KIO4 using 1,10-phenantroline (Phen) as an activator. The optimum conditions obtained are pH 4.5, 0.1 M acetate buffer solution, 4.0 x 10(-4) M KIO4, 4.5 x 10(-5) M CB+, 1.0 x 10(-4) M Phen, reaction temperature 40 C and reaction time of 4.0 min at 640 nm. Under the optimized conditions, the method allowed the measurement of Mn(II) in a range of 0.1-5.0 mu g L-1 with a detection limit of 0.023 mu g L-1. The recoveries in measuring the standard Mn(II) solutions of 0.5, 2.0 and 4.0 mu g L-1 were in the range of 97-103%, and the relative standard deviations (RSDs) were in a range of 3.0-0.8%. The method was applied satisfactorily to the determination of Mn(II) in some environmental water samples. The reliability of method was also verified by determining the manganese content of the certified standard reference river water sample, JAC-0031. Compared with the previously published catalytic-kinetic methods and instrumental methods, the method showed fairly good selectivity and sensitivity, low cost, cheapness, low detection limit and rapidity. It can easily and successfully be applied to the natural water samples.
Coupling of ion pair ultrasound assisted-cloud point extraction to microvolume UV-Vis spectrophotometry for speciation analysis of ionic NO2-,NO3-and total NO2-/NO3-without and with reduction in the selected beverage and food matrices
(Taylor & Francis Ltd, 2020) Olgac, Esra; Gurkan, Ramazan
This study proposes a simple, low-cost, easy to use, fast, accurate and reliable ultrasound assisted-cloud point extraction (UA-CPE) method for the enrichment and speciation analysis of low levels of ionic NO2-, NO(3)(-)and total NO2-/NO(3)(-)without and with reduction by micro-volume UV-vis spectrophotometry. The method relies on the reaction of NO(2)(-)with excess iodide at pH 5.5 to form triiodide, and then the extraction of the oxidation product formed by charge transfer into micellar phase of Triton X-114 using cationic redox-sensitive phenazine dye, neutral red (NRH+) as ion-pairing in absence and presence of 1.5 mL of 1.0 x 10(-3)mol L(-1)Br(-)ions. The main variables affecting extraction efficiency were studied and optimised in detail. Under the optimal conditions, the calibration curves in solvent were linear over the ranges of 5-100 and 100-1280 mu g L(-1)with a detection limit of 1.32 mu g L(-1)while the matrix-matched calibration curves prepared from sample extracts were linear over the ranges of 5-125 and 125-1350 mu g L(-1)with a detection limit ranging from 1.15 to 1.50 mu g L(-1)for sample matrices. From pre-concentration of 25-mL sample, pre-concentration and sensitivity enhancement folds of 62.5 and 76.5 were obtained. The accuracy/precision studies after spiking were performed, and observed to be in range of 96.5-99.6% and 1.9-5.7% (15, 75 and 250 mu g L-1, n: 5). The speciation analysis of ionic NO2-, NO(3)(-)and total NO2-/NO(3)(-)was performed from artificially prepared binary mixtures after reduction with a mixture of Zn and NaCl in acidic media. The free NO(3)(-)contents of samples were calculated from difference between free NO(2)(-)and total NO2-/NO(3)(-)contents. After validation by analysis of a certified sample, the method was successfully applied to the speciation analysis of the beverage, cured meat, vegetable and milk samples. After pre-treatment with two sample preparation steps, it was observed that the results obtained were also compatible with each other, statistically validating the method.
DEVELOPMENT OF A NEW ANALYTICAL METHODOLOGY BASED ON THE CATALYTIC EFFECT OF AG(I) IN A NEW FUCHSIN-PEROXODISULFATE-1,10-PHENANTROLINE SYSTEM: APPLICATION TO THE DETERMINATION OF TRACE AMOUNTS OF SILVER
(Soc Chilena Quimica, 2014) Gurkan, Ramazan; Ulusoy, Halil Ibrahim
A simple, rapid and sensitive kinetic spectrophotometric method is proposed for the determination of trace amounts of silver ion in the concentration ranges of 2-20 and 20-50 mu g L-1. The proposed method is based on the catalytic effect of Ag(I) on the oxidation reaction of new fuchsin by potassium peroxodisulfate in the presence of 1,10-phenantroline as an activator at pH:5.0. The reaction is followed spectrophotometrically by measuring the change in absorbance at 547 nm using the initial rate method during the indicator reaction of 5 minute. The reaction rate variables like pH, reagent and activator concentrations and effect of reaction time and temperature were optimized in order to achieve the maximum analytical sensitivity. The experimental and theoretical detection limits of the developed method were found as 0.475 mu g L-1 and 1.50 mu g L-1, respectively. The relative standard deviations for five replicate measurements of 15 and 35 mu g L-1 of Ag(I) were 5.27% and 3.32%, respectively. The effect of different diverse ions on the determination of silver was studied and found to be free from most interference. The method was successfully applied to the determination of silver in photographic solutions and different real water samples such as tap water, pond water and natural spring waters.
Dissolution Kinetics of Magmatic Rocks via Ultrasonic Leaching for Calcium, Magnesium and Aluminum
(Gazi Univ, 2008) Ozkan, Mehmet Hikmet; Gurkan, Ramazan; Ozkan, Aysun; Akcay, Mehmet
Ultrasound is known to enhance solid-liquid interface reactions. This study deals with the investigation of the dissolution of quartz monzonite from magmatic rock class in hydrochloric acid of 1.0% HCl (v/v) in the presence of ultrasound. Dissolution kinetics of ultrasonic leaching for destructive analysis of a magmatic rock sample was investigated. Various dissolution kinetics parameters such as dissolution order (n), dissolution rate constant (k), initial dissolution rate (r(i)) and maximum dissolution (S-max) were determined as the functions of the mass of sample, the grain size of sample and ultrasonication power for Ca, Mg and Al. The kinetic parameters were evaluated to reflect the quantitative aspect of the magmatic rock dissolution behavior.
Extraction and preconcentration of trace Al and Cr from vegetable samples by vortex-assisted ionic liquid-based dispersive liquid-liquid microextraction prior to atomic absorption spectrometric determination
(ELSEVIER SCI LTD, 2018) Altunay, Nail; Yildirim, Emre; Gurkan, Ramazan
In the study, a simple, and efficient microextraction approach, which is termed as vortex-assisted ionic liquid-based dispersive liquid-liquid microextraction (VA-IL-DLLME), was developed for flame atomic absorption spectrometric analysis of aluminum (Al) and chromium (Cr) in vegetables. The method is based on the formation of anionic chelate complexes of Al(III) and Cr(VI) with o-hydroxy azo dye, at pH 6.5, and then extraction of the hydrophobic ternary complexes formed in presence of cetyltrimethylammonium bromide (CTAB) into a 125 mu L volume of 1-butyl-3-methylimidazolium bis(trifluorosulfonyl) imide [C4mim][Tf2N]) as extraction solvent. Under optimum conditions, the detection limits were 0.02 mu g L-1 in linear working range of 0.07-100 mu g L-1 for Al(III), and 0.05 mu g L-1 in linear working range of 0.2-80 mu g L-1 for Cr(VI). After the validation by analysis of a certified reference material (CRM), the method was successfully applied to the determination of Al and Cr in vegetables using standard addition method.
Extraction and reliable determination of acrylamide from thermally processed foods using ionic liquid-based ultrasound-assisted selective microextraction combined with spectrophotometry
(TAYLOR & FRANCIS LTD, 2018) Altunay, Nail; Elik, Adil; Gurkan, Ramazan
Acrylamide (AAm) is a carcinogenic chemical that can form in thermally processed foods by the Maillard reaction of glucose with asparagine. AAm can easily be formed especially in frequently consumed chips and cereal-based foods depending on processing conditions. Considering these properties of AAm, a new, simple and green method is proposed for the extraction of AAm from thermally processed food samples. In this study, an ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate, [Bmim][BF4]) as extractant was used in the presence of a cationic phenazine group dye, 3,7-diamino-5-phenylphenazinium chloride (PSH+, phenosafranine) at pH 7.5 for the extraction of AAm as an ion-pair complex from selected samples. Under optimum conditions, the analytical features obtained for the proposed method were as follows; linear working range, the limits of detection (LOD, 3S(b)/m) and quantification (LOQ, 10S(b)/m), preconcentration factor, sensitivity enhancement factor, sample volume and recovery% were 2.2-350 mu g kg(-1), 0.7 mu g kg(-1), 2.3 mu g kg(-1), 120, 95, 60 mL and 94.1-102.7%, respectively. The validity of the method was tested by analysis of two certified reference materials (CRMs) and intra-day and inter-day precision studies. Finally, the method was successfully applied to the determination of AAm levels in thermally processed foods using the standard addition method.
Indirect determination of the flavor enhancer maltol in foods and beverages through flame atomic absorption spectrometry after ultrasound assisted-cloud point extraction
(ELSEVIER SCI LTD, 2017) Altunay, Nail; Gurkan, Ramazan; Orhan, Ulas
A simple ultrasound assisted-cloud point extraction (UA-CPE) method was developed and combined with flame atomic absorption spectrometry (FAAS) for pre-concentration and indirect determination of the flavor enhancer maltol in foods and beverages. The method is based on reduction of Cu(II) to Cu(l) by maltol at pH 6.5, and subsequent selective interaction of Cu(I) with bathocuproine (BCP) to form a ternary complex in presence of sodium dodecyl sulfate (SDS). Under the optimized conditions, pre-concentration of a 35 mL sample solution allowed detection of 1.24 mu g L-1 maltol in a linear range of 4-230 mu g L-1. The method was validated by intra- and inter-day precision studies ranging from 2.1 to 3.4%, and recoveries ranged from 93.3% to 104.4% using standard addition method. After pretreatment with two different sample preparation steps assisted by ultrasound energy, the proposed method was applied successfully for determination of maltol in selected foods and beverages. (C) 2017 Elsevier Ltd. All rights reserved.
Innovative and practical deep eutectic solvent based vortex assisted microextraction procedure for separation and preconcentration of low levels of arsenic and antimony from sample matrix prior to analysis by hydride generation-atomic absorption spectrometry
(ELSEVIER SCI LTD, 2019) Altunay, Nail; Elik, Adil; Gurkan, Ramazan
Considering the negative impacts on human health and the environment, determinations of arsenic (As) and antimony (Sb), is of unquestionable importance. The present study describes the development of innovative and practical deep eutectic solvent (DES) based vortex assisted microextraction (DES-VAME) method for preconcentration of As and Sb from environmental waters, honey and rice prior to analysis by hydride generationatomic absorption spectrometry (HG-AAS). The use of As(III) and Sb(III) in presence of dithizone at pH 10.5 by means of donor-acceptor mechanism were decided as analyzes. Total As and Sb were determined after reduction process. The analytical properties obtained following optimization were as follows. Limit of detection (LOD), precision (as RSD%), recoveries and enhancement factor for As and Sb were calculated as 7.5 ng L-1/1. 5.6 ng L-1, 2.1% /2.7%, 93.5%/96.2% and 104/85, respectively. Following validation with certified reference material, the method was successfully applied to the analysis of real samples.
Ion pair vortex assisted-ionic liquid based dispersive liquid-liquid microextraction for selective separation and preconcentration of 4-methylimidazole from caramel colour drinks and foodstuffs prior to its spectrophotometric determination
(ELSEVIER SCIENCE BV, 2019) Altunay, Nail; Gurkan, Ramazan
In the study, a simple, fast, easy to use, cost-effective and green analytical method was developed for the selective extraction and determination of 4-methylimidazole (4-MeI) from caramel colored drinks and foods by using vortex assisted-ionic liquid-based dispersive liquid liquid microextraction (VA-IL-DLLM) followed by spectrophotometry. The method is based on ion-pairing of the formed anionic chelate complex, AgIm(ImH)(H2N-C(CH2OH)(2)(CH2O)(-) (in fact, where the charged chelate formation and concentration dependent charge transfer proceeds together in aqueous IL medium), between soft Ag+ ions and 4-MeI with cationic soft IL, trihexyl (tetradecyl)phosphonium chloride, Cyphos IL 101 in presence of chelating and redox sensitive biological tris buffer at pH 7.0, and then extraction of the formed ion-pair into the micro-droplets of the IL by help of vortex. Greener IL, Cyphos IL 101 as both extractant and ion-pairing was effectively used together with the dispersive solvent (ethanol) for separation of analyte from sample matrix in extraction process. The important factors influencing extractable ion-pair formation and extraction efficiency were evaluated and optimized in detail. The method has shown a low limit of detection and quantification, LOD and LOQ (1.15 and 3.82 mu g L-1) and excellent linearity (4-500 mu g L-1) with a regression coefficient (r(2) = 0.9917) via calibration based on aqueous standard solutions of 4-MeI in solvent. Also, a validation study was performed on the spiked two quality control samples (honey and tea) at levels of 25, 100 and 300 mu g L-1 by means of matrix-matched calibration curves. The method showed good analytical features such as LODs (1.27, 1.42 mu g L-1), LOQs (4.24, 4.73 mu g L-1), recovery% (91.5-96.3%), repeatability (3.5-6.2%) and reproducibility (4.1-7.6%) without a significant matrix effect in linear working ranges of 5-350 and 4-400 mu g L-1 respectively as a measure of accuracy and precision with a sensitivity enhancement factor of 115-fold. After the validation, the method was successfully applied to the determination of low levels of 4-MeI in caramel colour drinks and foodstuffs. The findings have shown that the method is promising for accurate and reproducible detection of 4-MeI in the selected samples with acceptable analytical results.
Ionic liquid based ion-pairing microextraction combined with spectrophotometry for preconcentration and quantitation of melamine in milk and milk-based products
(ELSEVIER SCIENCE BV, 2017) Altunay, Nail; Demir, Ozge; Gurkan, Ramazan
A simple, rapid and economical ultrasound-assisted microextraction (UA-ME) procedure was developed for extraction and determination of trace amounts of melamine in milk products, followed at 310 nm by UV-Visible spectrophotometry. In the study, 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide [C(6)mim][Tf2N] as ionic liquid (IL) was used in presence of sodium dodecyl sulfate (SDS) as an oppositely charged auxiliary ligand at pH 4.0 for extraction of melamine, and methanol was selected as a disperser solvent. Under the optimal conditions, the analytical features of method were established by calibration curves prepared from both solvent based calibration and matrix-matched calibration solutions. The method exhibits a linear relationship (from 5 to 250 mu g L-1), low detection limit (1.6 mu g L-1), good recovery (93.5-97.8%), and high sensitivity enhancement factor (125) by solvent based calibration curve while it allows a detection limit of 2.1 mu g L-1 in range of 5-210 mu g L-1 by the matrix-matched calibration curve. The method accuracy (trueness and precision) was checked by applying matrix-matched calibration strategy to all the spiked samples including quality control samples as well as comparison with an independent micellar LC method, and then it was successfully applied to the determination of melamine in milk based products. (C) 2017 Elsevier Ltd. All rights reserved.
A micellar improved method for trace levels selenium quantification in food samples, alcoholic and nonalcoholic beverages through CPE/FAAS
(ELSEVIER SCI LTD, 2013) Ulusoy, Halil Ibrahim; Yilmaz, Oznur; Gurkan, Ramazan
A useful preconcentration and determination method was proposed for trace selenium in food samples. The procedure is based on complex formation of Pyronine B with Se(IV) ions in the presence of sodium dodecyl sulphate (SDS) and Ponpe 7.5. The variables affecting complex formation, extraction and phase separation were studied and optimised. Under the experimental conditions used, the calibration graph was linear in the range of 20-1700 mu g L-1 for Se(IV) ions. The limit of detection was 3.81 mu gL(-1) of Se(IV) and the relative standard deviation for 5 replicate determinations at 250 mu g L-1 concentration level was 2.45%. Recovery values were obtained between 97.8%" and 102.8% for spiked samples. The method was successfully applied to the determination of total selenium in some food samples and alcoholic and nonalcoholic beverages. Its validity was checked by the analysis of four certified reference materials. The results obtained by the proposed method were quantitatively in good agreement with the certified values. (C) 2013 Elsevier Ltd. All rights reserved.
Micellar-Sensitized Spectrophotometric Determination of Magnesium in Drinking Water
(Iser Publications, 2009) Gurkan, Ramazan; Ulusoy, Halil Ibrahim; Akcay, Mehmet
A sensitive and relatively selective spectrophotometric method is proposed for the rapid determination of magnesium using Eriochrome black T (EBT) as a complexing agent in the presence of N-cetyl-N, N, N-trimethylammonium bromide (CTAB). The complex formation reaction between EBT and magnesium (II) is instantaneous in presence of NH3/NH4Cl buffer at pH 9.5 after CTAB adds as micellar-sensitized medium and the absorbance as analytical signal remains stable for over 6 h. N-cetyl N, N, N-trimethylammonium bromide as cationic surfactant and Triton X-100 as nonionic surfactant are used for improving the sensitivity and solubility of the analytical system, respectively. The surfactant-sensitizing method allows the determination of magnesium in the concentration range of 0.05-1.2 mu g mL(-1) with a molar absorption coefficient of 8928 L mol(-1) cm(-1) and Sandell's sensitivity of 2.82 ng cm(2-). The method has a detection limit of 0.012 mu g mL- 1 (DL=3S(b)/m) and quantification limit of 0.054 mu g mL-1 (QL=10S(b)/m) at an analytical measurement wavelength of 640 nm with a bathochromic shift of 86 nm. The selectivity of chelating reagent was improved by the use of 1 mL masking agent solution containing 0.1 mol L-1 EDTA, 0.01 mol L-1 triethanolamine and 5000 mu g NaF mL(-1). The proposed method has been successfully applied to the determination of magnesium at trace levels in different drinking water samples. The precision (with CV of 2.35%) and the accuracy obtained were highly satisfactory.

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